Sounds awful expensive for a Demo - to compare a similar situation, I remember my 2011 335d demo that had 12K miles - MSRP was 53K and cap cost was $39K with only first month, tax, and DMV fees. Monthly was $499 / month.

As another poster said, what you are paying you should be getting a new X3.

My new X5 diesel I just picked up last month, is $625 / month so I think $615 is way too high IMO.